1. Field of the Invention
The present invention relates to a semiconductor development apparatus and more particularly to a knife edge ring capable of easily discharging developer and cleaning solution remaining on a bottom surface of a wafer during semiconductor manufacturing.
This application claims priority from Korean Patent Application No. 10-2006-0015335, filed Feb. 16, 2006, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein.
2. Discussion of Related Art
Semiconductor devices are manufactured by repeatedly performing various processes such as diffusion, oxidation, deposition, photolithography and cleaning. In the photolithography process, a photosensitive film made of a photoresist is coated on the wafer with a predetermined thickness, the wafer is exposed to light using a reticle in which a desired pattern is designed, and the exposed photosensitive film is removed through a developing process. During this developing process, a wafer to be exposed is rotated at a constant speed while a predetermined amount of developer is supplied on the wafer. A cleaning solution is then supplied to the bottom surface of the rotating wafer. The wafer is then withdrawn and mounted on a top surface of a bake plate and baked at a predetermined temperature.
As the developer is supplied to the upper surface of the rotating wafer, the developer moves toward the edge by centrifugal force and some of the developer forms a liquid droplet on the wafer's bottom surface. In addition, the cleaning solution directed to the wafer's bottom surface may not be entirely discharged. This remaining solution may form another liquid droplet toward the edge of the wafer's bottom surface. When these droplets combine to form a large size droplet, this droplet may remain on the edge of the wafer's bottom surface. When the wafer undergoes the baking process, this large liquid droplet migrates toward the side of the wafer and is vaporized. This vaporization causes chemical material to deposit at the periphery of the top surface of the edge of the wafer. This chemical material acts as a contaminant and compromises circuit patterning at the wafer's edge. This results in product loss due to a reduction in the amount of useable wafer.